Escalators and elevators are two of the most popular means for moving pedestrian traffic from a first elevation to a second elevation. Elevators are typically used when the rise is greater than two floors, and the passenger volume light to moderate. Escalators, in contrast, are typically used when the rise is three floors or less and the passenger volume moderate to heavy. Despite each means targeting a different need, it is very common today for existing buildings to have both escalators and elevators, thereby capitalizing on the advantages of both.
Historically, handicapped pedestrian traffic has been limited to elevators because of the inability of escalators to accept handicapped passengers, in particular those in wheelchairs. Handicap access in existing buildings has been provided, therefore, by having either elevators alone or both escalators and elevators. Today, however, the trend in almost all types of buildings is towards less expensive two and three story buildings which can be operated more efficiently. The cost of installation and maintenance, coupled with the unrentable occupied space, make providing both escalators and elevators a less popular option than in the past. Passenger traffic and handicap access must still be satisfied, however.